The use of a floppy disk as rotating magnetic recording media is well known. More specifically, a single disk is known to be permanently encased in a protective jacket. The disk rotates within the jacket, as the jacket is held stationary.
While flexible diskette devices have proved to be very useful in the art, certain problems have been encountered. A flexible plastic jacket is provided to protect the disk, but its ability to do so is limited by the nature of the material from which the jacket is made. The disk can be dented when a sharp object falls on the envelope. Users have also wrapped the jacket and disk about a related computer printout, causing the flexible assembly to permanently warp. Another common problem is fingerprint oil on the disk's recording surface.
In addition, centering and clamping of the disk occurs while the disk is constrained somewhat from sideways movement. This can lead to poor centering, and/or damage to the disk in the vicinity of its central mounting opening. This same movement constraint can cause the disk's rotational torque requirement to change from one diskette to another, and/or can produce inconsistent head-to-disk compliance.
In its generic form, a prior art disk jacket includes two generally central apertures, located in aligned fashion, in the opposite flat surfaces of the jacket. These openings allow access to the disk's central aperture, so that the disk may be clamped and rotated within the stationary jacket. Other jacket openings or slots allow access for a magnetic transducing head(s) which reads or writes onto the magnetic recording layer(s) of the moving disk.
The disk may be clamped to a motor by means of a rigid hub which is permanently attached to the disk. However, for economic reasons it is preferred that the disk drive include a spindle and collet which close onto and clamp the flexible disk media at the location of the disk's central aperture.
The art of floppy disk rotating magnetic memory or recording devices has long recognized the need to include a means for cleaning the disk as it rotates within its stationary jacket.
U.S. Pat. No. 3,668,658 is exemplary. This patent shows a flexible disk permanently enclosed in a protective flexible cover, envelope or jacket. In this patent the two inner jacket surfaces, which confront the opposite planar surfaces of the flexible disk, include a solid, porous, antistatic cleaning material. This material is in continuous frictional contact with the adjacent surfaces of the disk. As the disk rotates, this material operates to clean the disk. This patent also suggests the use of a head load-unload pinch pad which pinches the flexible outer surfaces of the jacket together to provide additional disk cleaning action by the jacket's inner porous layers. U.S. Pat. No. 4,038,693 shows such a pinch pad, which is force-loaded into the side of the flexible disk jacket only after the disk has been centered and clamped by the disk drive's spindle/collet mechanism.
The disk/jacket assembly of aforementioned U.S. Pat. No. 3,668,658 is a flexible assembly, i.e. neither the disk nor its jacket is rigid.
A form of rigid assembly is shown in U.S. Pat. No. 3,864,755 wherein a flexible disk is encased within a jacket formed of a relatively rigid, flat, first cover, to which a thin second cover is deformed, to provide a cavity coextensive with the circumferential outer edge of the flexible disk. This cavity is fully lined by two wiper layers which always engage the opposite flat surfaces of the disk.
The concept of placing a flexible disk in a protective rigid jacket having two rigid walls is shown, for example, in U.S. Pat. No. 4,149,207. In this patent the flexible disk integrally carries a drive hub; whereas, in the former patents the drive interface to the disk is formed by releasably clamping the flexible disk material itself.
This later patent provides a relatively thick cavity for the disk. A pair of oppositely disposed, protruding wiper elements continuously engage the opposite planar surfaces of the disk, and thus the disk tends to be maintained centered within this thick cavity.
Copending and commonly assigned U.S. patent application Ser. No. 343,635, filed Jan. 28, 1982, now abandoned, also discloses a flexible disk placed in a protective rigid jacket having two rigid walls. In this device, the two rigid jacket halves are identical in that both contain a head access opening and both contain a 90.degree. displaced, internally projecting boss which controls a disk cleaning material on its upper surface. When the two jacket halves are assembled, the access openings are 90.degree. displaced from each other. The boss of one jacket half is then opposite the access opening of the other jacket half, and both sides of the disk are wiped, as each boss provides a pressure force for a magnetic head.
In known prior art, where the relatively fragile flexible disk material is itself clamped to the disk drive's spindle/collet mechanism, the construction and arrangement either provides no cleaning capability, or when cleaning is provided, the cleaning means continuously engages the disk, and prevents free sideways movement of the disk during clamping.
This lack of free disk movement during clamping can result in damage to the relatively fragile disk in the vicinity of its central opening. In addition, inaccurate centering of the disk about the drive's spindle may occur. It is conventional in disk drives of the floppy disk type to merely position the head where a disk track should be--and where the track will be if the disk is accurately centered. As a result of the aforementioned lack of free disk movement during clamping, the disk tracks may be mislocated relative the disk drive's head.